Xylene production processes employing rhenium-containing catalysts

Abstract

Processes for making xylene employ catalysts containing rhenium and a molecular sieve component comprising an acidic MFI molecular sieve having a Si/Al 2 molar ratio of less than about 80 and mordenite to provide a transalkylation product with a low content of benzene co-boilers. The invention encompasses the use of sulfided catalyst embodiments in xylene production processes.

1. A process for producing xylene, the process comprising: contacting a feed stream comprising an aromatic hydrocarbon having at least seven carbon atoms with a catalyst at aromatic conversion conditions including the presence of hydrogen comprising at least one of a transalkylation reaction, disproportionation reaction, and isomerization reaction and producing a product stream having an increased concentration of xylene relative to the feedstream wherein the catalyst comprises a mordenite component; an acidic MFI molecular sieve component having a Si/Al 2  molar ratio of less than about 40; a rhenium component ranging from about 0.05 to about 5 mass percent of the catalyst; and a rhenium-dispersing binder. 
     
     
       2. The process of  claim 1  wherein the Si/Al 2  molar ratio of the acidic MFI molecular sieve component is less than about 25. 
     
     
       3. The process of  claim 1  wherein the Si/Al 2  molar ratio of the mordenite component is less than about 40. 
     
     
       4. The process of  claim 1  wherein the binder comprises alumina. 
     
     
       5. The process of  claim 1  wherein the catalyst further comprises a sulfur component. 
     
     
       6. The process of  claim 5  wherein the atomic ratio of sulfur to rhenium is between about 0.2:1 and about 0.7:1. 
     
     
       7. The process of  claim 5  wherein the rhenium component is present in an amount between about 0.4 and about 5 mass percent of the catalyst. 
     
     
       8. The process of  claim 1  wherein the acidic MFI molecular sieve component has a Total Acidity of at least about 0.25. 
     
     
       9. The process of  claim 1  wherein the mass ratio of the acidic MFI molecular sieve component to the mordenite component is in the range of about 1:10 to 5:1. 
     
     
       10. The process of  claim 1  wherein the acidic MFI molecular sieve component is a steamed MFI molecular sieve. 
     
     
       11. The process of  claim 1  wherein the mordenite component comprises between about 20 to about 80 mass percent of the catalyst; the acidic MFI molecular sieve component comprises between about 10 and about 70 mass percent of the catalyst; and the binder comprises between about 1 and about 40 mass percent of the catalyst. 
     
     
       12. The process of  claim 1  wherein the feed comprises toluene and wherein the aromatic conversion conditions are toluene disproportionation conditions; the process further comprising a temperature ranging from 200° C. to about 600° C., a hydrogen to hydrocarbon mole ratio ranging from about 0.2 to about 0.5, a pressure ranging from about 100 kPa to about 6 MPa absolute, and a weight hourly space velocity (WHSV) ranging from about 0.2 hr −1  to about 20 hr −1 . 
     
     
       13. The process of  claim 1  wherein the aromatic conversion conditions are transalkylation conditions; the process further comprising a temperature ranging from 100° C. to about 540° C., a pressure ranging from about 100 kPa to about 6 MPa absolute, and a weight hourly space velocity (WHSV) ranging from about 0.1 hr −1  to about 20 hr −1 . 
     
     
       14. The process of  claim 13  wherein the feed stream has an Ending Boiling Point of at least about 210° C. 
     
     
       15. The process of  claim 14  wherein the product stream has an Ending Boiling Point at least 10° C. lower than that of the feed stream. 
     
     
       16. The process of  claim 13  wherein the feed stream comprises C 9   +  aromatics. 
     
     
       17. The process of  claim 16  wherein the feed stream further comprises at least one of benzene and toluene. 
     
     
       18. The process of  claim 16  wherein the feed stream comprises between about 5 and about 30 mass percent of C 10   +  aromatics. 
     
     
       19. The process of  claim 16  wherein at least about 0.5 mass percent of the total C 9   +  aromatics in the feed stream are polycyclic aromatics. 
     
     
       20. The process of  claim 16  wherein at least about 20 mole percent of the total C 9   +  aromatics in the feed stream are consumed and at least about 70 mole percent of the consumed C 9   +  aromatics are converted to aromatics having a lower molecular weight.